The present invention relates to a communication apparatus, a communication method, and a communication system for performing a communication over a network.
In recent years, the IP protocol, i.e., the standard protocol in the Internet, has substantially become the standard protocol in the field of communications. Accordingly, the IP protocol is now in wide use such as mails and Web accesses. The IP protocol that is in the mainstream at present is a one according to the specification referred to as “IPv4”. In contrast to this, a specification referred to as “IPv6” whose address space is largely extended has been defined. The IP addresses defined by the IPv6, which have a 128-bit address space, make it possible even to assign global IP addresses fixedly to all the appliances and sensors existing all over the world. Refer to, e.g., Literature 1: RFC2373, R. Hinden and S. Deering, “IP Version 6 Addressing Architecture”, July 1998, pp. 1-26.
Meanwhile, T. Narten et al. of IBM have proposed the following privacy-protecting method: A transmission-source appliance itself generates, at random, an interface ID that occupies the lower 64 bits of an IPv6 address, thus generating a temporary IPv6 address which is effective only in a connection unit or in a time-period such as 1 day or 1 week. Next, the transmission-source appliance uses either the temporary IPv6 address or the permanent IPv6 address depending on the case, thereby protecting privacy. Refer to, e.g., Literature 2: T. Narten et al., “Extensions to IPv6 Address Autoconfiguration”, RFC 3041, January 2001.